Exploiting multiple exciton effects in organic solar cells

利用有机太阳能电池中的多重激子效应

• 批准号: 1604524
• 负责人: Barry Rand
• 金额: $ 32.96万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1604524&HistoricalAwards=false
• 关键词: Exploiting; multiple; exciton; effects; organic

The sun represents the most abundant potential source of sustainable energy on earth. Solar cells that use organic conducting polymers to convert light to electricity ? organic photovoltaic (OPV) devices - offer a potentially low-cost route for renewable electricity production. However, in order to achieve parity with other solar photovoltaic technologies, organic solar cells must increase their power conversion efficiency. This project will incorporate light-active materials into the organic polymer solar cell device to promote a quantum mechanical process called triplet fusion. It is believed that triplet fusion can increase the voltage of the power output, leading to higher solar energy conversion efficiency. This concept is innovative from a scientific point of view because it will focus on increasing the voltage potential, not the photocurrent, leading to a pathway to increase solar cell efficiency through an increase in thermodynamic efficiency. The educational activities associated with this project include participation in the Princeton University Materials Academy that teaches hands-on materials science to under-represented high school students from the Trenton, New Jersey, and multi-generational outreach through the Nano Materials Science Day at a local library that encourages students, teachers, and parents to meet with solar scientists and participate in hands-on demos to make and test simple solar cell devices. The overall goal of the research is to develop a new, organic polymer-based excitonic solar photovoltaic device architecture that has the potential exceed classical thermodynamic power conversion efficiency limits through the process of triplet fusion. In triplet fusion, two excitons formed from two low-energy sub band gap photons are required to produce one higher-energy photon. The integration of sensitized phosphorescent materials into the organic photovoltaic (OPV) device architecture offers the means to achieve triplet fusion. In a phosphor-sensitized OPV device, absorption and singlet formation occurs primarily on a fluorescent host donor. This initial absorption event is followed by energy transfer to a phosphorescent guest present in the donor layer at low concentration. Excitons on the phosphorescent guest then transfer to the triplet level of the host, permitting the population of the long-lived triplet state in the fluorescent material. This process of triplet fusion will be used to create free charge carriers with higher energy than the exciton from which the carriers originated. In essence, this device configuration represents the molecular analogue to an intermediate band solar cell, but possesses similar limiting efficiencies as singlet fission-based solar cells. The main distinction between the triplet fusion device and a conventional intermediate band solar cell is that, in the triplet fusion device, the intermediate band is satisfied via the fusion of two low energy triplet excitons into a higher energy singlet exciton. Furthermore, whereas the singlet fission device looks to increase photocurrent, the one based upon triplet fusion looks to increase the photovoltage, leading to fundamental enhancement of the thermodynamic efficiency. To explore this new phenomenon, the research has two major objectives. The first objective is to demonstrate the functionality of the phosphor-sensitized OPV device for achieving triplet fusion, and the second objective is to understand efficiency-limiting mechanisms involved with multiple exciton devices through comprehensive electrical and optical characterization. Ultimately, the demonstration of a triplet fusion OPV device adds another option to exceed Shockley-Queisser limits and inspire work toward high efficiency organic solar cells.

太阳是地球上最丰富的可持续能源的潜在来源。 使用有机导电聚合物将光转化为电的太阳能电池？有机光伏（OPV）器件--为可再生电力生产提供了一条潜在的低成本途径。 然而，为了达到与其他太阳能光伏技术同等的水平，有机太阳能电池必须提高其功率转换效率。 该项目将在有机聚合物太阳能电池设备中加入光活性材料，以促进称为三重态聚变的量子力学过程。 据信，三重态聚变可以增加功率输出的电压，从而导致更高的太阳能转换效率。从科学的角度来看，这个概念是创新的，因为它将专注于增加电压电势，而不是光电流，从而通过增加热力学效率来提高太阳能电池效率。 与该项目相关的教育活动包括参与普林斯顿大学材料学院，该学院向来自新泽西特伦顿的代表性不足的高中生教授实践材料科学，并通过当地图书馆的纳米材料科学日进行多代推广，鼓励学生，教师，与太阳能科学家见面，并参加动手演示，制作和测试简单的太阳能电池设备。该研究的总体目标是开发一种新的基于有机聚合物的激子太阳能光伏器件架构，该架构具有通过三重态聚变过程超过经典热力学功率转换效率限制的潜力。 在三重态聚变中，需要由两个低能量子带隙光子形成的两个激子来产生一个较高能量的光子。 将敏化磷光材料集成到有机光伏（OPV）器件架构中提供了实现三重态熔合的手段。 在磷光体敏化的OPV器件中，吸收和单重态形成主要发生在荧光主体供体上。该初始吸收事件之后是能量转移到以低浓度存在于供体层中的磷光客体。 磷光客体上的激子然后转移到主体的三重态能级，允许荧光材料中的长寿命三重态的布居。这种三重态熔合过程将用于产生自由电荷载流子，其能量高于载流子起源的激子。 本质上，这种器件配置代表了中间带太阳能电池的分子类似物，但具有与基于单线态裂变的太阳能电池相似的限制效率。 三重态熔合装置与常规中间带太阳能电池之间的主要区别在于，在三重态熔合装置中，中间带通过两个低能量三重态激子熔合成较高能量单重态激子来满足。此外，单重态裂变装置看起来增加光电流，而基于三重态聚变的装置看起来增加光电压，导致热力学效率的根本提高。 为了探索这一新现象，本研究有两个主要目标。 第一个目标是证明用于实现三重态融合的磷光体敏化OPV器件的功能，第二个目标是通过全面的电学和光学表征来理解与多个激子器件相关的效率限制机制。最终，三重态聚变OPV装置的演示增加了另一种选择，以超过Shockley-Queisser极限，并激发高效有机太阳能电池的工作。